Many wireless communication devices maintain a local time that may be used to provide time information to time-dependent applications, such as calendar applications, alarm applications, and the like. Due to their mobility, wireless communication devices are often transported between time zones. When a wireless communication device is transported to another time zone, the device's local time needs to be synchronized to the current time zone so that a valid local time can be provided to time-dependent applications.
Some wireless carriers transmit Network Identity and Time Zone (NITZ) messages including embedded information which wireless communication devices can use to derive a current time zone. However, the timing of sending a NITZ message is often at the discretion of the serving network. Accordingly, a wireless communication device may not be sent an updated NITZ message upon transitioning from one time zone to another. As such, a device that has transitioned between time zones may provide an incorrect local time to time-dependent applications, which may not function as expected by the user due to the incorrect local time.
Even when a recent NITZ message is available to a wireless communication device, there can be some ambiguity as to a time zone derived from a NITZ message. In this regard, due to varying implementation of Daylight Savings Time (DST) rules, multiple time zones can match parameters included in a NITZ message at certain times of the year. For example, the State of Arizona in the United States does not implement DST. At certain times of the year, there can be ambiguity as to whether time zone parameters in a NITZ message indicate that a user is located in the America/Phoenix time zone or in the America/Denver time zone. While selecting either time zone can provide an accurate local time for a user at least temporarily, errors can result around the time of DST transitions. In this regard, if America/Denver is selected as the time zone for a user located in Arizona, the user's local time can be incorrect when the America/Denver time zone transitions from Mountain Standard Time (MST) to Mountain Daylight Time (MDT).